1. Field of the Disclosure
The present invention relates generally to high-voltage integrated circuits utilized with power converters and, more specifically, the present invention relates to the semiconductor devices and device structures, and processes for fabricating high-voltage integrated circuits.
2. Background
Many electrical devices, such as cell phones, personal digital assistants (PDA's), laptops, etc., utilize power to operate. Because power is generally delivered through a wall socket as high voltage alternating current (ac), a device, typically referred to as a power converter, can be utilized to transform the high voltage ac input to a well regulated direct current (dc) output through an energy transfer element. Switched mode power converters are commonly used due to their high efficiency, small size, and low weight to power many of today's electronics. In operation, a switch is utilized to provide the desired output quantity by varying the duty cycle (typically the ratio of the on-time of the switch to the total switching period), varying the switching frequency, or varying the number of pulses per unit time of the switch in a power converter.
A power converter may use a controller, which is generally an integrated circuit, to provide output regulation to an electrical device (generally referred to as a load). The power converter may include a circuit which provides power to the controller during the start-up of the power converter. In one example, the power converter may use a resistor to provide the start-up function. The resistor may provide a high voltage dc from an output of a bridge rectifier or winding to the controller. During start-up, the high voltage dc provided by the resistor may be used to charge a capacitor for the controller. The capacitor may also provide power to the controller after start-up. In another example, a voltage regulator may be utilized in lieu of a resistor to perform the start-up function.
Corresponding reference characters indicate corresponding components throughout the several views of the drawings. Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of various embodiments of the present invention. Also, common but well-understood elements that are useful or necessary in a commercially feasible embodiment are often not depicted in order to facilitate a less obstructed view of these various embodiments of the present invention.